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DAVIS ON THE COLORADO RIVER PROBLEM 387
lands feasible of irrigation in the United States, including the Mohave Valley lands.
Nature has provided two feasible dam sites that will utilize all the head Available here, without submerging the Mohave Valley. One of these sites is above, at Bulls Head, and one below, near the mouth of Williams River. The latter is necessary for a high diversion dam for the Parker-Gila Valley Project, the construction of which the author assumes. It would be built to the greatest height possible without damage to the City of Needles, or about 100 ft. The proposed dam in Mohave Canyon would conflict with this, and would also submerge the dam site at Bulls Head, just above the Mohave Valley. It would leave undeveloped 40 ft. of power head below Boulder Canyon, which would thus be lost.
The dam site in the Mohave Canyon was examined twenty years ago and at intervals since by various engineers, including William Mulholland and J. B. Lippincott, Members, Am. Soc. C. E., and on account of the destruction of land, water, and other property, was unanimously regarded as infeasible, and for this reason, its foundations were not explored. Any money spent thereon would be wasted for reasons already given. It was never seriously advocated until it became necessary to kill the proposal to build a dam in Boulder Canyon and develop enough power to repay the cost. This emphasizes the real point at issue, that is, whether the immense resources of the Lower Colorado are to be retained in the control of the Federal Government or turned over to private corporations. This is a question on which engineers and others may honestly differ, and which the speaker will not discuss. It should be considered on its merits, and not combatted indirectly to the great sacrifice of the natural resources of land and water.
Wanton Destruction of Valuable Storage.—Perhaps the most destructive feature of the author's plan is the proposed building of a high dam at Devils Slide, thus restricting the height of the Boulder Dam to 387 ft., and its storage capacity to about 10,000,000 acre-ft. Such a reservoir would rapidly fill with sediment, and thus be destroyed much earlier than necessary.
It has been shown that large storage capacity is necessary to convert the Colorado River from a destructive torrent into a source of vast wealth, and that this storage will steadily be destroyed by silting. Yet, here is a proposal to build a high dam in the middle of the best reservoir site in the Basin, and thus wantonly destroy its value. It is idle to reply that other reservoirs can be provided above, because these are of limited capacity, and, therefore, of limited life; moreover, they do not intercept all the water nor all the silt.
Proper Plan of Development.—The plan of development proposed herein is shown on Fig. 21 (a) as compared with that proposed by the author on Fig. 21(6).
The speaker's plan would be to build the Boulder Dam to a height sufficient to back up water to the dam site at Bridge Canyon. This dam would impound about 28,500,000 acre-ft. of water, control floods more perfectly than any smaller reservoir, and develop power more cheaply than any smaller dam, in sufficient quantity to repay its cost with interest.